The invention relates to a method and an apparatus for changing the label magazine boxes of labeling machines.
In modern labeling machines, the labels to be affixed to containers, and in particular to bottles, are individually and successively picked up by gluing segments and then transferred to a gripper cylinder which in turn transfers the label that has been coated with glue while on the gluing segment to the container to be labeled.
Since in high-speed labeling machines the label box is emptied in about five minutes, there is the problem of refilling the magazine box with labels. The label magazine boxes can be refilled by hand only with difficulty since usually a number of magazine boxes are disposed one on top of the other at the pickup point. The lowermost box contains the belly label, and the one above it the breast label; and above that two further boxes may be disposed, one for the neck label and one for the foil to be wrapped around the top of the bottle. This is why the boxes are accessible practically only from the rear for the purpose of refilling.
There have been many proposals for automating the refilling of label boxes. For example, German patent application DOS 21 16 912 describes a refilling apparatus of this type in which the labels are pushed by means of a plunger from supply boxes disposed on a turntable into the label box which is in the pickup position. Since the labels must be pushed up in the label box continuously, even during the refilling operation, at the rate at which they are picked up, the transfer of the stack of labels pushed by the plunger into the label box to that conveying means is rather complicated and still requires semimanual operation.
Pickup of the labels poses still another problem that is a factor in the refilling of the label boxes. To avoid malfunctioning of the labeling machine, the label box located in the pickup position is always retracted from the pickup means when there is no container at the labeling point. This retracting of the label box is triggered by sensors located at the conveying path of the containers to be labeled. To permit this retracting of the label box, sufficient space must be provided, and the mass to be moved in retracting the label box must not be excessive. This is not necessarily the case with prior-art refilling apparatuses of the type disclosed in the aforesaid German patent application DOS 21 16 912. Besides, there the retracting movement of the label box would conflict with the advancing movement in refilling the label box, that is to say, the label box could not be retracted during refilling, or then only with great difficulty.